Field of the Invention
The present invention relates to an information processing apparatus, a method for controlling an information processing apparatus, a gripping system, and a storage medium.
Description of the Related Art
When image capturing target objects have high glossiness, and faces of the image capturing target objects are arranged so as to form a reentrant angle, multiple times of light reflection, i.e., multiple reflection, is likely to occur between the image capturing target objects. Multiple reflection is also called mutual reflection, since the reflection mutually occurs between the image capturing target objects. If multiple reflection occurs, objects that face each other are unexpectedly reflected in the image capturing target objects in a captured image. If usual image processing is applied in a state where the unexpected reflection occurs, the portion of the unexpected reflection is affected by the other area.
In particular, unexpected reflection has significant influence in an active distance measurement device that uses one-dimensional line light projection or two-dimensional pattern light projection and measures the distance to an image capturing target object.
With the active distance measurement device, the distance is measured using the principle of triangulation, based on the direction in which projected light exits from an illuminating device and the direction in which the projected light enters an image capturing device after being reflected at the image capturing target object.
When an image capturing target object has a high surface scattering property, a large part of the light entering the image capturing device from the image capturing target object is primary reflected light, and accordingly the distance measurement using the principle of triangulation effectively works. However, if the aforementioned unexpected reflection occurs due to multiple reflection, the incident direction of the projected light will be incorrectly recognized, and an error occurs in the measured distance, resulting in noise generation.
Japanese Patent Laid-Open No. 2009-145175 discloses a method by which noise is removed using the characteristics of the way noise is generated due to multiple reflection. With this method, it is determined that noise has been generated and the noise is then removed if the angle formed between a face that directly faces the distance measurement device and the direction of a vector connecting the measurement point of interest and an adjacent measurement point is large. This method uses a characteristic that the noise generated by multiple reflection is likely to have a steep characteristic with respect to the face that directly faces the distance measurement device.
Japanese Patent No. 3800842 discloses a method by which noise is removed using a characteristic that an image is inverted due to reflection occurring an even number of times. With this method, the increasing and decreasing direction of spatial codes on a captured image obtained with pattern light projected from a projection device is determined in advance, and it is determined that multiple reflection has occurred, if the increasing and decreasing direction of the spatial codes is opposite to the determined increasing and decreasing direction of the codes. This method uses the characteristic that an image is inverted due to reflection occurring an even number of times, and the fact that a dominant component of multiple reflected light is a secondary reflected light component.
However, with the method described in Japanese Patent Laid-Open No. 2009-145175, a noise point generated by multiple reflection can be effectively removed, but meanwhile, there are cases where a measurement point that is not noise is incorrectly determined to be noise and is removed, since a relationship between a measurement point of interest and an adjacent measurement point is also steep near a step between objects.
Similarly, with the method described in Japanese Patent No. 3800842, a noise point generated by multiple reflection occurring an even number of times can be favorably removed, but meanwhile, there are cases where the increasing and decreasing direction of the spatial codes also becomes opposite near a step between objects, and accordingly, a nearby measurement point is removed, and a lack of information regarding the measurement point near the step affects the accuracy in some cases.
The present invention has been made in view of the foregoing problem, and provides a technique for reducing both the influence of noise generated by multiple reflection and the influence of a side effect of noise removal processing on information processing that uses measured distance values.